Alloy



Patented Apr. 23, 1929.

- UNITED STATES TRIEDEBICK I BECKET, OF NEW YORK, N. Y., ASSIGNOR. 'I'O ELECTRO METALLURGI- CAL COMPANY, A CORPORATION OF WEST VIRGINIA.

PATENT OFFICE.

ALLOY.

No Drawing.

The invention relates to alloys of nickel and molybdenum containing considerable quantities of iron, and minor quantities of silicon, manganese, carbon and other elements. The alloys of the invention are particularly valuable for their acid-resistingproperties but they are also adapted for uses where acidresistance is not essential.

Alloys of this type are disclosed in Patents 1,37 5,082 and 1,37 5,083 to Clement. The patentee was aware of the acid-resisting properties of the'alloys, and apparently regarded an alloy containing nickel 90% and molybdenum 10% as the optimum composition, although he observed that up to 10% of iron could be added without destroying the useful properties.

I have discovered that much better acidresistance can be obtained by increasing the molybdenum beyond the proportion recommended by Clement, and I have found it possible, by using a proper proportion of molybdenum, to make alloys which contain 20% or more of iron and still show better acid-resistance than the alloys disclosed by Clement.

The alloys of my invention are resistant to hydrochloric. acid and to sulphuric acid, but are attacked by nitric acid. There is no in crease in acid resistance obtainable by rais- 1 ing the molybdenum above'about 40%, or at least none suflicient to warrant the cost of the higher molybdenum content.

The molybdenum can be most cheaply introduced into the alloy as lerromolybdenum,

but this material can only be used where the final alloy is not too much impaired by the iron so introduced. I find that alloys containing 15% or more of molybdenum give a tolerance for iron suflicient to warrant their preferment. With the molybdenum at or above18% the alloy may contain substantial quantities of iron and still show excellent acid-resistance; higher in fact than iron' i'ree alloys containing less than 15% molybdenum. Giving due consideration to cost and properties I regard a molybdenum content of about 20% as the most desirable one.

A series of carefully prepared and analyzed alloys were tested in the forged condition for Application filed January 10, 1928. Serial No. 245,811.

resistance to 10% HCl at 70 C. These alloys had the following approximate composition:

Per cent.

Mo 20 Ni+Fe 77 Mn 2.2 v 0.3 S1 0.2 y C 0.2

The iron content was varied through a number of values in the test. The acid-resistance was found-to fall oil as the iron content increas'edthe decrease in acid-resistance being slow until the iron content reached about All the alloys with less than 35% iron had acceptable acid-resistance, the weight loss in this test not exceeding 0.00015 grams per square centimeter per hour for any of the samples within this range.

I prefer that the percentage of iron present shall not be greater than five times the amount by which themolybdenum percentage exceeds 10. Thus, with a molybdenum content of 15% the iron may be as high as 25%, while with molybdenum 18%- the iron may be as high as 40%. My tests indicate, however, that the nickel content should not fall below 4.0%. With the molybdenum in the higher ranges the permissible iron content is limited by this consideration rather than by the relation of iron to molybdenum stated above. The preferred content of iron is still loWer-- not more than 30% even with the optimum molybdenum for high iron content. The preleast 40%, molybdenum to 40%; and a percentage of iron not less than 10% nor greater than five times the amount by which the molybdenum percentage exceeds 10.

2. An alloy consisting essentially of nickel,

molybdenum and iron; containing nickel at.

least 40% molybdenum 18% to 40% and not 20 less than 10% nor more than 30% of iron.

3. An alloy containing molybdenum 18 to and iron between 10% and with the balance chiefly nickel.

In testimony whereof, I affix my signature.

' FREDERICK M. BECKE'I. 

